Power factor correction method and device

Abstract

A power factor correction method and the controller thereof, applied to a boost-type converter, are provided. First, the power factor correction method uses the input and output voltages to generate a reference switching signal. Next, a voltage control circuit uses the difference between the output voltage and a voltage command to get a duty phase. Then, the switching control signal is determined by shifting the phase of the reference switching signal according to the duty phase. Finally, a comparator compares the switching control signal with a triangle waveform signal to determine the switching signal. A power factor controller, which utilizes this method, uses only a single voltage control circuit to get the switching signal to regulate the output voltage and shape the current waveform without sensing current and a current control circuit, so that the complexity of the invented control circuit for the power factor correction is reduced dramatically.

1 . A power factor correction method, applied to a boost-type converter, comprising steps of:
 producing a duty phase according to an output voltage of said boost-type converter and a voltage command;   producing a reference switching signal according to an input voltage of said boost-type converter;   producing a switching control signal by shifting said reference switching signal with said duty phase;   producing a triangle waveform signal; and   producing a switching signal by comparing said switching control signal with said triangle waveform signal.   
     
     
         2 . The power factor correction method in  claim 1 , wherein the step of producing said duty phase is to calculate a difference between said output voltage and said voltage command, and then to produce said duty phase according to said difference. 
     
     
         3 . The power factor correction method in  claim 1 , wherein the step of producing said reference switching signal is to divide said input voltage by said voltage command. 
     
     
         4 . The power factor correction method in  claim 1 , wherein the step of producing said reference switching signal is to divide said input voltage by said output voltage. 
     
     
         5 . The power factor correction method in  claim 1 , wherein the step of producing said reference switching signal is to divide said input voltage by the average voltage of said output voltage in a switching period. 
     
     
         6 . A power factor controller, applied to a boost-type converter, comprising:
 a voltage circuit, which receives an output voltage of said boost-type converter and a voltage command to output a duty phase;   a reference switching signal generator, which receives an input voltage of said boost-type converter to produce a reference switching signal;   a phase shifter, which receives said duty phase and said reference switching signal to produce a switching control signal;   a triangle wave generator, which generates a triangle waveform signal; and   a comparator, which compares said switching control signal with said triangle waveform signal to produce a switching signal.   
     
     
         7 . The power factor controller in  claim 6 , wherein said voltage circuit is a proportional-integral controller. 
     
     
         8 . The power factor controller in  claim 6 , wherein said reference switching signal generator comprises an absolute value retriever. 
     
     
         9 . The power factor controller in  claim 8 , wherein said reference switching signal generator comprises a divider further. 
     
     
         10 . A power factor controller, applied to a boost-type converter, comprising:
 a voltage circuit, which receives an output voltage of said boost-type converter and a voltage command to output a duty phase;   a reference switching signal generator, which receives an input voltage and said output voltage of said boost-type converter to produce a reference signal and a switching signal amplitude;   a phase shifter, which receives said duty phase and said reference signal to produce a phase-dependent signal;   a multiplier, which receives said phase-dependent signal and said switching signal amplitude to produce a switching control signal;   a triangle wave generator, which generates a triangle waveform signal; and   a comparator, which compares said switching control signal with said triangle waveform signal to produce a switching signal.   
     
     
         11 . The power factor controller in  claim 10 , wherein said voltage circuit is a proportional-integral controller. 
     
     
         12 . The power factor controller in  claim 10 , wherein said reference switching signal generator comprises an absolute value retriever, a maximum retriever, a first divider, an average retriever and a second divider.